This invention is directed to improving the performance of a tool for conditioning a semiconductor polishing pad.
In the production of integrated circuits the wafer on which the circuits are constructed is subjected to repetitive chemical mechanical polishing, or planarization, steps. Polishing is performed on a resilient pad in conjunction with a chemical slurry.
The production of quality circuits is dependent in large measure on proper conditioning, or reconditioning, of the polishing pad. Conditioning of the pad, which can be done after a wafer has been polished (ex-situ) or as the wafer is being polished (in-situ), is essentially a roughening and flattening of the pad surface. Thus, the conditioning tool is a body having an abrasive surface which is pressed against and moved across the pad.
U.S. Pat. No. 5,842,912, granted Dec. 1, 1998 to Holzapfel et al. for xe2x80x9cApparatus for Conditioning Polishing Pads Utilizing Brazed Diamond Technologyxe2x80x9d discloses a pad conditioning apparatus. U.S. Pat. No. 5,954,570, granted Sep. 27, 1999 to Yano et al. for xe2x80x9cConditioner for a Polishing Toolxe2x80x9d, discloses a pad conditioning tool.
Both Holzapfel et al. and Yano et al. recognize that the conditioning tool should be mounted flexibly to permit the tool to have planar contact with the pad being polished. They include a ball and socket connection in the drive system above the tool. The pivot point of the ball and socket connection is a substantial distance above the abrasive surface of these tools so drag forces acting laterally across the tool surface act through a substantial moment arm tending to tilt the tool excessively and producing chatter, or vibration of the tool. The result can be uneven conditioning of the polishing pad.
There continues to be a need for a conditioning tool that is stable and reliable in operation.
This invention contemplates forming the conditioning tool with a body member having an abrasive peripheral lower surface and a central recess from the upper surface. A holder for the tool extends into the recess in the body member and an elastomeric member between the holder and the body member holds the latter two components together. There is clearance between the holder and the body member and the elastomeric member acts as a gimble and permits the body member to tilt with respect to the holder for planar contact with the surface of the pad being polished.